Automatic vehicle location (AVL) devices are known in the art. Typically, an AVL unit operates to determine the position of a vehicle using dead reckoning techniques, Loran C monitoring, or monitoring of telemetry information as provided by global positioning system satellites. With such information, AVL units are able to at least approximately determine the geographic position of the unit itself, and hence an associated monitored object, such as a vehicle.
Often, it is desired to transmit this derived location information to a remote base site. For example, the AVL unit may be installed in a delivery truck, and the location information is preferably communicated to a delivery dispatcher who will make appropriate use of the location information. To accommodate this, prior art AVL units are typically operably connected to a radio transceiver that communicates on a voice resource or a data resource. (Many voice resources support data messages as well, such as resource assignment information, status message updates, and the like. As used herein, however, "voice resource" is intended to refer to a communication resource that is primarily intended for voice messaging, but which may also support short data messages of the type just referred to. "Data resource," on the other hand, is intended to refer to a data message only system, or substantially data only, wherein the data messages are not related to system protocol but rather are intended to convey system-independent information between two or more users.)
In prior art systems, the AVL user must select either a voice transceiver or a data transceiver to communicate the location information developed by the AVL unit. This remains so even if the vehicle to be monitored includes both a voice transceiver and a data transceiver. Voice resources and data resources, however, have different advantages and disadvantages, including traffic limitations, range, accessibility, and the like. A need exists for an AVL unit that can obtain the benefits of both voice transceivers and data transceivers when they are available.